Testing integer vs float value

[chaawuu]

suppose i have:
int a = 12;
int b = 19;
float c = a / b;

The value for c is a float. How would I test whether or not it was an integer, or a whole number?

 

[qednick]

You can use the floor() function:

first you need to #include "math.h" in the appropriate header file.

What floor() does is return the integer value of a double/float.

Therefore:

double d = 123.456;
double e = floor(d); // the value of e is now 123.0

So... in this context, you can check whether a double/float has an integer value:

if (d == floor(d))
{
// we know that d is a whole integer
}

To get the fractional part of a double/float you could:

double d = 123.456;
double fPart = d - floor(d);

// the value of fPart is now 0.456


A similar function called ceiling() will return the next highest integer value above a double/float:

double d = 123.456;
double c = ceiling(d);

// the value of c is now 124.0


Now, just to add the icing on the cake so to speak, try to use doubles instead of floats. They tend to be more accurate.

 

[victorv]

hi,

another trik is to test the remainder of integer division:

if( a%b )
there is a remainder


or

int a,b,x
float f
....
x=a/b
f=(float)a / (float)b
if( (float)x!=f )
f had decimal part


bye